Re: [PATCH 1/2] ARM: dts: BCM5301X: Specify serial console parameters

From: "Rafał Miłecki" <zajec5@gmail.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org,
	Florian Fainelli <f.fainelli@gmail.com>,
	Hauke Mehrtens <hauke@hauke-m.de>,
	Russell King <linux@armlinux.org.uk>,
	Rob Herring <robh+dt@kernel.org>,
	bcm-kernel-feedback-list@broadcom.com,
	Rafa?? Mi??ecki <rafal@milecki.pl>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/2] ARM: dts: BCM5301X: Specify serial console parameters
Date: Tue, 14 Mar 2017 13:37:13 +0100	[thread overview]
Message-ID: <aab82e4c-803e-34d7-5455-ba905b91bde4@gmail.com> (raw)
In-Reply-To: <3345fb38-fbea-141e-6ad2-a3341e2c31fe@gmail.com>

On 03/14/2017 01:32 PM, Rafał Miłecki wrote:
> On 03/14/2017 01:26 PM, Andrew Lunn wrote:
>> On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote:
>>> From: Rafa?? Mi??ecki <rafal@milecki.pl>
>>>
>>> This adds baud rate, parity & number of data bits. It's required to get
>>> serial working correctly.
>>>
>>> Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl>
>>> ---
>>>  arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++-
>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi b/arch/arm/boot/dts/bcm5301x.dtsi
>>> index 8fd1ef9f0c2d..468107166a6f 100644
>>> --- a/arch/arm/boot/dts/bcm5301x.dtsi
>>> +++ b/arch/arm/boot/dts/bcm5301x.dtsi
>>> @@ -18,8 +18,12 @@
>>>  / {
>>>      interrupt-parent = <&gic>;
>>>
>>> +    aliases {
>>> +        serial0 = &uart0;
>>> +    };
>>> +
>>>      chosen {
>>> -        stdout-path = &uart0;
>>> +        stdout-path = "serial0:115200n8";
>>>      };
>>
>> Hi Rafal
>>
>> The alias is fine. But putting the stdout-path here is unusual. Which
>> serial port is used for console is board specific, where as
>> bcm5301x.dtsi is very generic, it describes the SoC, not a board.  If
>> you look at other .dtsi files, those that specify stdout-path contain
>> properties which are common to a range of similar boards.
>
> So far I've never seen any board using other uart. Also uart0 is disabled by
> default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 /
> BCM47094). I think it's just more practical to have simple DTS that covers
> 99,9% boards by default and handled that margin of devices separately.
>
> We already got a lot of duplicated code for enabling uart0, see:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd
>
> Jon Mason from Broadcom who knows this hardware and designs very well confirmed
> it's a sane/safe assumption.

That was supposed to be "any other uart or parameters".

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